| Popis: |
Some reactions of 4-substituted flavans have been studied. 4-Chloro/bromo derivatives react under neutral conditions with phthalimide and acetonitrile leading to displacement or axial halogen by nitrogen with inversion. In contrast, irrespective of the stereochemistry, 4-hydroxy-derivatives react under acidic or basic conditions leading to axial attack by the nudeophiles SOCl2, PCl3, PCl5, SOBr2, PBr3, PBr5, acetonitrile and water, evidently through the intermediate formation of a benzylic carbocation. |
